I have not cast either the 8 1/2'/#4 or 5. In that length I might favor the 4 and stick to 9' for the 5. Given the opportunity I would, as I often recomend, cast them at a fly shop. I did cast the 8'9"/#4 Circa and while lovely and super slender for a fan of deliberate action rods it is what we called back when a "wet fly" action rod as opposed to ONE's "dry fly" action.

I should add, in keeping with this thread's Helios content, that the new H2 8 1/2'/#4 will be out by trout season and I was told in both a mid and tip-flex version. The H1 mid-flex only rod in that size was the Helios sweet spot and if the new one is improved as much as the new #5's are (light of day better), it is a potential contender. Also I anticipate Clutch Fly Rods model in that size may be available by spring too. Many new rods to look forward to. I don't recall if we have done a forum thread on rod model line "sweet spots" but they absolutly exist.